Pneumatic reciprocating valve



United States Patent O essaies PNEUMATIC REQIPRCATING VALVE Kenneth K.. Kroihe, Parma, Ghia, assigner to Airmatic Valve, Inc., Cleveiand, (Ehio, a corporation oi @trio Filed Aug. 15, 1966, Ser. No. 572,416 9 Claims. (Ci. 91-396) This invention relates to a pneumatically actuated reciprocating valve assembly and has particular reference to a reciprocating four way spool valve for controlling a reciprocating double acting pneumatic cylinder or pump. The present invention provides an improved, completely pneumatic system for shifting the spool or a four way valve for controlling the reciprocation of a double acting power cylinder, pump, or the like. Pneumatic control means are provided for controlling the time of each stroke of rthe power cylinder, and means may also be provided to adjust the dweil time between each stroke so that by use of the invention it is possible to independently control each portion of the cycle of operation of the power cylinder.

It is the principal object of the invention to provide a new and improved valve for automatically reciprocating a power cylinder.

A further object of the invention is to provide `a control valve for a reciprocating power cylinder in which it is possible to independently vary the time of each stroke of the cylinder and the dwell time between strokes.

The foregoing, as well as other objects, will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawings illustrating preferred embodiments of the invention, wherein:

FIGURE 1 is a sectional View with parts in elevation of a valve according to the invention;

FIGURE 2 is a sectional view taken 'along line 2--2 of FIGURE l; and

FIGURE 3 is a sectional view with parts in elevation of a modied form of the invention.

In FIGURE 1 there is illustrated a valve comprising a valve body having an faxial bore 12 therein lined by sleeve 14. A valve spool 16 is reciprocally confined within `the sleeve 14 and is provided on its outer periphery with a series of G-rings 1S separated by portions of reduced diameter as shown. The valve body 10 may be counted on a base 2u with `a gasket 22 therebetween. The valve body is provided with a pressure duid inlet port 24, -a pair of work ports 26 and 2S, and a pair of exhaust ports 30 and 32, all of which communicate with the interior of the bore 12 through apertures in sleeve 14. The exhaust ports 3% and 32 communicate with iiow control valves 34 and 36 respectively. Each iiow control valve is provided with a metering valve member 3S which may be adjustably seated in bore itl by a rotating stem 42 so as to meter the flow of pressure uid passing from .the respective exhaust ports 3d, 32 through bore 4% to outlet 44 in base 2h of the valve. Work ports 46 and 48 in base 2@ are connected to work ports 26 and 2S respectively in valve body lil and may be connected to a power cylinder S0 by pressure lines as indicated in FIGURE 1.

Pneumatically operated valve controls 52 and 54 are mounted on opposite ends of the valve body 10. The valve controls 52 and 54 may be of identical construction and each includes la block 56 having an end wall 58 closing one end of bore 12 :and a cylindrical cap 60 secured to the block 56 to deline a cylindrical piston chamber 62.

Poppet 64 is normally seated by spring 68 against a valve seat 65 at the end of bore 66 in face 58 to prevent pressure uid flow from the bore i2 to atmosphere 3,385,166 Datented May 28, 1968 ICC through exhaust passage 70. When in this position, poppet stem 72 extends through the reduced portion of bore 66 land into the piston chamber 62. Piston 74 is reciprocally conned within chamber 62 and is normally positioned against the chamber end face 76 by spring 78.

Passages 80 extend from inlet port 24 to restricted orices leading to passages 81 in blocks 56 which communicate with bores 66 so that each end of spool 16 is normally exposed to the inlet uid pressure. Passages 84 run from work ports 26 and 23 to the ends of the adjacent piston chambers 62.

With the valve spool 16 positioned as in FIGURE 1 the inlet port 24 is connected through the right hand passage 30, restricted orice 82, passage 81, and bore 66 to the right hand end of bore 12 through a central opening in spring retaining washer 92. Likewise, the left hand end of bore 12 is maintained at inlet pressure by pressure fluid Flowing from inlet port 24 through the corresponding left hand passages so that the spool 16 is pressure balanced within the bore 12. Pressure lluid from inlet port 24 also Hows through work ports 23 and 48 to extend the piston in power cylinder 50. The opposite end of cylinder 50 is exhausted through work ports 46 and 26 to exhaust port 30 and then to atmosphere through flow control valve 34. Control valve 34 is adjusted to achieve the desired rate of operation of power cylinder 50i. At this time pressure tiuid also ows from work port 28 through orifice 84 to the right hand chamber 62 to the right of piston 74, causing the piston to shift to the left against spring 78 and abut end 72 of poppet 64. During the stroke of power cylinder Sti the work chamber thereof is expanding so that the pressure applied against piston 74 is less than line pressure and is insutcient to unseat poppet 64. When the stroke of the power cylinder is completed the fluid pressure in the power cylinder and in chamber 62 builds up to full line pressure and the increased force exerted on piston 74 is suicient to move it to the left to unseat the poppet 64. Because the pressure in chamber 62 is not built up to line pressure until the expansion stroke of power cylinder 5t) is completed, the poppet 64 cannot be unseated until after the completion of the power cylinder stroke.

With the unseating of poppet 64, the pressure at the right hand side of spool 16 is vented to atmosphere through exhaust and spool 16 is immediately shifted to the right hand end of bore 12 by the line pressure reacting on the left hand end of the spool.

With the spool shifted to the right hand end of bore 1 2, the work port 28 is connected to exhaust port 32 and the inlet port 24 is connected to work port 26 so that uid pressure flows through work port 46 to the other side of power cylinder Sti to initiate the return stroke of the work piston while the other side of the power cylinder is exhausted to atmosphere through work ports 4? and 28, exhaust 'port 32, liow control valve 36 and outlet 44. The speed of the return stroke of cylinder 50 is determined by the setting of exhaust flow control valve 36. When the spool 16 shifts to the right, the right hand chamber 62 is also exhausted to atmosphere through pa c-way 34 and work port 28 so that the piston 74 is g in seencd against the end face 76 by spring 78 and poppet 64 is then seated against the end of bore 66 by spring 68 so that the right hand end of spool 16 is again subjected to pilot pressure from inlet 24.

With the return stroke `of power cylinder 50 the left hand chamber 62 is subjected to work pressure from work port 26 through passage 84 which moves the piston '74 of valve unit 54 against the end of its poppet 64. When the return stroke of the power cylinder 5G is completed the line pressure moves left hand piston 74 to the right to unseat its poppet 54 and vent the line pressure in. the left end of bore 12 to atmosphere. The line pressure in the right end of bore 12 immediately shifts thespool back to the left to the position shown in FIG- URE 1 to complete the cycle of operation of the valve.

As long as pressure is maintained in inlet 24 power cylinder 50 will reciprocate with the speed of each stroke determined by the setting of the exhaust flow controls 34 and 36. It should be noted that the invention as shown in FIGURE 1 is positive acting in that the spool 16 cannot shift until after the stroke of the power cylinder 50 is completed and the pressure has built up to full line pressure in the piston chamber 62 of the appropriate valve unit 52 or 54. However, as soon as a poppet valve is opened upon completion of a work stroke, full line pressure is available to rapidly shift the spool in the opposite dire-ction. This feature represents a marked improve ment over conventional pneumatic reciprocating valves, and makes it impossible to reverse the spool before the completion of the full power cylinder work stroke. The positive action of the valve described herein assures that the power cylinder 50 is reciprocated throughout its full work stroke and eliminates possible premature movement of the spool 16.

The valve 110 in FIGURE 3 is identical to that shown in FIGURE l with the exception that the valve controls 152 and 154 are modified to provide an adjustable dwell time following each stroke of the power cylinder 150, With the spool 116 positioned as shown in FIGURE 3, pressure iiuid flows from inlet port 12,4 through work ports 128 and 148 to one side of the power cylinder 150 to extend the same. The other side of power cylinder 150 is exhausted to atmosphere through work ports 146 and 126, exhaust port 130, and control valve 134 as in the valve shown in FIGURE 1. Pressure fluid flows through passage 184 and is metered through adjustable needle valve 20G to that portion of piston chamber 162 to the right of piston 174. The needle valve 260 slows the build-up of pressure to the right of piston 174 so that there is a time delay from the time the stroke of power cylinder 151) is completed until pressure is built up in chamber 162 sufficient to shift piston 174 completcly to the left to unseat poppet 164 and shift the spool 116.

The duration of the interval between the end of the work stroke of power cylinder 150 and the unseating of poppet 164 is determined by the setting of the needle valve 20G, and may be varied over a wide range so that the dwell time at the end of the work stroke of power cylinder 150 may be varied as desired. A ball type check valve 202 connects the right hand end of piston chamber 162 with passageway 184 to provide immediate pressure relief of the chamber 162 when the piston 174 is returned to the right hand end thereof after the spool valve has shifted. Valve control 154 is similar to valve control 152 so as to obtain a dwell after the return stroke of power cylinder 150.

With the exception of the adjustable dwell time after the powe-r strokes of the cylinder 150, the valve shown in FIGURE 3 operates similarly to the valve shown in FIGURE 1. The exhaust flow controls 134 and 136 are independently adjustable so that .by properly setting needle valve 200 and the flow control valves 134 and 136 it is possible to independently adjust the timingr of each stroke of the power cylinder 150 and the duration of the dwell time between each stroke.

It is also within the scope of the invention to provide a valve of the kind shown in FIGURE l wherein one of the valve units 52 or 54 is replaced by a valve unit like that shown in FIGURE 3 so that a dwell will be obtained at the end of one stroke of the power cylinder but not on the return stroke.

While I have illustrated and described preferred ernbodiments of my invention, it is understood that these are capable of modication, and I therefore do not wish to be limited to the precise details 4set forth but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

What I claim as my invention is:

1. A pneumatically actuated reciprocating valve for alternately supplying pressure uid to opposite ends of a power cylinder or the like, comprising a valve body having a bore therein, an inlet port and a pair of work ports communicating with said bore, a valve spool reciprocab'le in said bore and operable upon reciprocation thereof alternately to connect each work port with said inlet port and the other work port to exhaust, means connecting said work ports to opposite ends of the power cylinder, passage means connecting said inlet port to opposite ends of said bore to supply pressure uid to opposite ends of said valve spool, each said passage means including a restricted orifice therein, an exhaust passage communicating with each end of said bore and Aa normally closed poppet valve in each said exhaust passage, pressure 4responsive means associated with each of said poppet valves and means connecting each work port with one of said pressure responsive means for actuating the latter, said pressure responsive means being operable upon actuation thereof to open the poppet valve associated therewith and exhaust one end of said bore thereby to permit the pressure fluid in the opposite end of said bore to shift said spool toward said one end of said bore, said pressure responsive means being operable to open their respective poppet valves only upon completion of a work stroke by the power cylinder.

2. A valve according to claim 1 wherein said pressure responsive means are operable to open their respective poppet valves upon an increase in pressure in their respective work ports.

3. A valve according to claim 2 wherein said pressure responsive means each comprise a chamber communieating with one of said work ports, a piston in said chamber engageable with said poppet valve, spring means urging said piston out of engagement with said poppet valve, said piston being shifted to open said poppet valve when the pressure supplied thereto through said one work port is greater than the pressure existing in such work port during the work stroke of said power cylinder.

4. A valve according to claim 3 including an adjustable valve means in the passage connecting one of said chambers to its Work port to restrict fluid ow to such chamber thereby to provide a time delay between completion of a work stroke of said power cylinder and shifting of said valve spool.

5. A valve according to claim 4 including a by-pass passage around adjustable valve means and a check valve in said by-pass.

v6. A valve according to claim 1 including adjustable valve means controlling the rate of exhaust of said power cylinderthereby regulating the speed of the work stroke thereof.

7. A pneumatically actuated reciprocating valve for alternately supplying pressure fluid to opposite ends of a power cylinder or the like, comprising a valve body having a bore therein, an inlet port, a pair of work ports and a pair of exhaust ports communicating with said bore, a valve spool reciprocable in said bore and operable upon reciprocation thereof alternately to connect each work port with said inlet port and one of said exhaust ports, means connecting said work ports to opposite ends of the power cylinder, passage means connecting said inlet port to opposite ends of said bore to supply pressure fluid to opposite ends of said valve spool, an exhaust passage communicating with each end of said bore and a norm-ally closed valve in each said exhaust passage, pressure -responsive means associated with each of said valves and means connecting each work port with one of said pressure responsive means for actuating the latter, said pressure responsive means being operable upon actuation thereof to open the valve associated therewith and exhaust one end of said bore thereby to permit the pressure uid in the opposite end of said bore to shift said spool toward said one end of said bore, and means to prevent actuation of said pressure responsive means until completion of a work stroke by the power cylinder.

8. A valve according to claim 7 including an adjustable valve means associated with each said exhaust port to regulate the rate of exhausting of said power cylinder.

9. A valve according to claim 8 including1 adjustable valve means in the connections between said work ports and said pressure responsive means to restrict iluid liow to the latter thereby to provide a time delay between i@ completion of a work stroke and shifting of said valve spool.

References Cit-ed UNITED STATES PATENTS Re. 7,420 12/1876 Cameron 91-307 335,855 2/1886' Toole 91--307 2,964,013 12/1960 Mitchell et al 91-306 l() MARTN P. SCHWADRON, Primary Examiner.

PAUL E. MASLOUSKY, Examiner. 

1. A PNEUMATICALLY ACTUATED RECIPROCATING VALVE FOR ALTERNATELY SUPPLYING PRESSURE FLUID TO OPPOSITE ENDS OF A POWER CYLINDER OR THE LIKE, COMPRISING A VALVE BODY HAVING A BORE THEREIN, AN INLET PORT AND A PAIR OF WORK PORTS COMMUNICATING WITH SAID BORE, A VALVE SPOOL RECIPROCABLE IN SAID BORE AND OPERABLE UPON RECIPROCATION THEREOF ALTERNATELY TO CONNECT EACH WORK PORT WITH SAID INLET PORT AND THE OTHER WORK PORT TO EXHAUST, MEANS CONNECTING SAID WORK PORTS TO OPPOSITE ENDS OF THE POWER CYLINDER, PASSAGE MEANS CONNECTING SAID INLET PORT TO OPPOSITE ENDS OF SAID BORE TO SUPPLY PRESSURE FLUID TO OPPOSITE ENDS OF SAID VALVE SPOOL, EACH SAID PASSAGE MEANS INCLUDING A RESTRICTED ORIFICE THEREIN, AN EXHAUST PASSAGE COMMUNICATING WITH EACH END OF SAID BORE AND A NORMALLY CLOSED POPPET VALVE IN EACH SAID EXHAUST PASSAGE, PRESSURE RESPONSIVE MEANS ASSOCIATED WITH EACH OF SAID POPPET VALVES AND MEANS CONNECTING EACH WORK PORT WITH ONE OF SAID PRESSURE RESPONSIVE MEANS FOR ACTUATING THE LATTER, SAID PRESSURE RESPONSIVE MEANS BEING OPERABLE UPON ACTUATION THEREOF TO OPEN THE POPPET VALVE ASSOCIATED THEREWITH AND EXHAUST ONE END OF SAID BORE THEREBY TO PERMIT THE PRESSURE FLUID IN THE OPPOSITE END OF SAID BORE TO SHIFT SAID SPOOL TOWARD SAID ONE END OF SAID BORE, SAID PRESSURE RESPONSIVE MEANS BEING OPERABLE TO OPEN THEIR RESPECTIVE POPPET VALVES ONLY UPON COMPLETION OF A WORK STROKE BY THE POWER CYLINDER. 